Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.
Typically, turbine blades are formed from a root portion at one end and an elongated portion forming a blade that extends outwardly from a platform coupled to the root portion at an opposite end of the turbine blade. The blade is ordinarily composed of a tip opposite the root section, a leading edge, and a trailing edge. The inner aspects of most turbine blades typically contain an intricate maze of cooling channels forming a cooling system. The cooling channels in the blades receive air from the compressor of the turbine engine and pass the air through the blade. The cooling channels often include multiple flow paths that are designed to maintain all aspects of the turbine blade at a relatively uniform temperature. However, centrifugal forces and air flow at boundary layers often prevent some areas of the turbine blade from being adequately cooled, which results in the formation of localized hot spots. Localized hot spots, depending on their location, can reduce the useful life of a turbine blade and can damage a turbine blade to an extent necessitating replacement of the blade.
Cooling channels forming a cooling system in a turbine blade often include a plurality of trip strips protruding from the walls of the channels. As cooling air flows through the cooling channel, a boundary layer is formed. The trip strips create vortices in cooling air flowing through the channel thereby increasing the effectiveness of the cooling channels. The trip strips are generally aligned orthogonal to the air flow through the cooling channel. However, in some conventional cooling systems, the trip strips may be aligned at an angle to the flow of cooling air. As cooling air passes over the angled trip strips, vortices are created immediately downstream of the trip strip and move along the trip strip from an end furthest upstream toward the downstream end of the trip strip. As the vortices propagate along the length of the trip strip, the boundary layer becomes progressively more disturbed or thickened, and consequently the tripping of the boundary layer becomes progressively less effective. The net result of the thickening or growth of the boundary layer in significantly reduced heat transfer enhancement that is typically associated with thin vortices formed by trip strips. Thus, a need exists for a cooling channels capable of increasing the heat transfer enhancement action of the trip strips.